SULTAN ­— Some of the best whitewater river rapids in the Northwest came roaring back to life over the weekend.

Snohomish County PUD officials opened the gate at Culmback Dam on Friday, Saturday and Sunday, allowing high flows to rush through a 14-mile long canyon on the Sultan River.

That area normally almost runs dry in the fall. But when water is running high through, the narrow gorge it becomes a rarity for kayakers — a long, continuous stretch of Class IV rapids just one hour from a major metropolitan area.

“It was really wonderful out there,” said Tom O’Keefe, Pacific Northwest stewardship director for American Whitewater. “Sometimes you want to go through something big. Other times you really want to try finesse your way down and kind of thread your way through.”

About 50 top-level kayakers rode the waves over the three days, braving nonstop rapids and rainy, cold weather. Rapids are ranked in five classes. Paddlers in the advanced to expert range can handle Class IV.

The water that used to flow through the upper reaches of the Sultan River now is diverted. It provides much of Snoho­mish County’s drinking water and also generates electricity at the PUD’s Henry M. Jackson Hydroelectric Facility.

Federal energy regulators are now relicensing the hydroelectric plant. The lengthy, bureaucratic review process has cracked open a door of opportunity for the kayaking community.

American Whitewater, a national advocacy group for kayakers, has asked the PUD to add controlled releases of water down the river as part of its management of the hydroelectric plant.

Releasing a deluge through the canyon was a test to see what water levels are necessary to provide kayakers with a quality paddling experience, said Bruce Meaker, a senior manager of regulatory affairs in the water resources division.

On Friday, flows of 325 cubic feet per second were released from Culmback Dam. The amount increased to 700 cubic feet per second on Saturday and went up to 900 cubic feet per second on Sunday. Rain runoff added to the flows. Normal flows from the dam are 20 cubic feet per second.

“I think the real question is: should the PUD be in a situation where we will artificially create a scheduled release to accommodate kayaking?” Meaker said. “When we do that, it’s water that we don’t get to run through the turbine, and therefore generate power.”

About 15 kayakers rode the rapids each day, filling out surveys on how well they enjoyed each flow level. O’Keefe said Saturday’s mid-flow option was the best, but added that flows were much higher than the 700 cubic feet per second release because the ample rain runoff flowing into the river and because the PUD allowed more water than expected into the gorge.

The kayakers say they want to carve out a few days of kayaking per year without reducing the utility’s ability to generate electricity and without harming endangered chinook salmon and steelhead that spawn in the river.

“The goal for American Whitewater is not to get a study,” said Andy Bridge, a kayaker from Sultan and a volunteer with the advocacy group. “We want at least a handful of days.”

The PUD is conducting more than 20 studies on the hydroelectric dam, including many on how it affects fish that spawn in the lower reaches of the river, Meaker said.

The utility believes that the dam and hydroelectric operation have had some positive impacts on chinook and steelhead because their spawning beds are protected from flooding. However, those species lost access to the upper reaches of the river in 1929 when a diversion dam was built to send water to Lake Chaplain, the city of Everett’s water reservoir.

The relicensing process requires the PUD to study whether it needs to take new steps to offset the impact its operation has on chinook and steelhead. Both fish species were listed as threatened under the federal Endangered Species Act, action that came after the project was built.

The PUD’s current license with the Federal Energy Regulatory Commission expires at the end of 2011, Meaker said. It’s 50 years old. A new license likely would last another 30 years to 50 years.

The hydroelectric generator produces 43 megawatts of power on average, enough to light and heat 36,000 typical homes.

Reporter Lukas Velush: 425-339-3449 or lvelush@heraldnet.com.